This invention generally relates to golf clubs and specifically to clubs for putting a golf ball into a hole.
Publications providing specifications, instruction and other data in the field of putting include “The Rules of Golf” from the United States Golf Association (2002), “Dave Pelz's Putting Bible” from Doubleday (2000), and “The Ultimate Clubmakers Catalog” from Golfsmith International, LP (2003).
Putting is a major component of scoring in the game of golf, often comprising about 40% of the strokes used. Putting is a precise activity with a very low error required for holing most putts. As putting requires low force but high accuracy, improvements for putters have greatest potential in facilitating a good stance and proper aim, and consistent stroking of the putter. The degree of achieving these requirements will vary with the skill level of the player as well as with playing conditions.
The putter disclosed herein has a weight distribution and form which enhances the player's ability to take a good stance and to minimize the potential or effect of mis-hits. It has an aiming mark which maximizes the player's ability to visualize alignment with the aimline, and a grip configuration which promotes consistent club face orientation and stroking direction. Further, this putter has a face with friction and energy transfer characteristics that corrects for errors in club face orientation or directional errors in stroking the putter, and it enhances ball motion after stroking.
Prior configurations have disclosed putters with the center of gravity in line with the intended impact point with the golf ball in order to help prevent putter face twisting for off-center hits, or to achieve a certain hitting characteristic. For instance see U.S. Pat. No. 5,938,538—Broadridge et al. (1999) that discloses a transverse and horizontal center of gravity location coincident with the ball strike point and shaft axis extension. However, the extension of the shaft axis intersects longitudinally near the front face, requiring some side resisting force from a player to keep the putter in the proper position. This shaft position relative to the center of gravity also promotes twisting of the putter on the backstroke. A further disadvantage of this longitudinal location of the shaft is to place the ball back in the stance, making aiming a putt more difficult. U.S. Pat. No. 6,350,208 B1—Ford (2002) has a larger head with the center of gravity vertically in line with the shaft hosel. However, the shaft is close to the strike face, still keeping the ball undesirably forward in the stance. A center of gravity close to the face also has the negative result of reducing the polar moment of inertia. Ford '208 is silent on the how the player positions the stance. U.S. Pat. No. 4,701,477—Solomon (1987) has the shaft rearward of the face but the center of gravity is forward of the shaft, creating a need for a resisting force when taking a stance. This increases tension in the player's hands and arms. Further, a shaft position behind the center of gravity promotes twisting of the putter on the downstroke. U.S. Pat. No. 4,754,976—Pelz (1988) discloses a putter with a special weight positioned away from the face that increases the polar moment of inertia. However, this putter cannot be made in one piece, which increases cost. None of these patents disclose how the center of gravity should be located with respect to the player and the pivot point of the swing, and none show inertia weighting that meets cost and dimensional requirements.
Many putters have soles which are curved transversely, for instance U.S. Pat. No. 4,141,556—Paulin (1979). This patent does not disclose any relationship to a player's stance and does not have a small enough transverse radius to allow for an ideal stance for some players. U.S. Pat. No. 6,406,379—Christensen (2002) has a smaller transverse radius, but its value is too large to optimize the hitting area when the putter is tipped transversely.
There are a variety of aiming marks disclosed for putters including that in U.S. Pat. No. 5,993,330—Akerstrom (1999). It has an alignment stripe that has a small length to width ratio making it difficult to establish directionality, and the color is not specified. U.S. Pat. No. 5,072,941—Klein (1991) discloses a wide sighting surface which is yellow on a black background, and which has a narrow black groove in the center. The wide surface has a small length to width ratio, and the small groove is too small to visualize accurately. The sighting surface in Klein '941 is also in three sections making it difficult to focus on that surface. U.S. Pat. No. 5,615,884—Modglin (1997) discloses a long alignment notch but which is too narrow and too small in area for clear visual focus, and which does not extend frontward to the top of the putter face.
Putter grips are routinely supplied with an axial flat portion that is aligned parallel to the direction of stroking. These current putters do not align the grip flat with any particular portion of a player's hand to allow accurate rotational orientation of the putter.
There are various surface conditions for a putter face now in use including various metals and elastomers. Also, several U.S. patents show materials that are intended to improve the player's perception of the ball striking process. For instance see U.S. Pat. No. 6,471,600 B2—Tang, et al. (2002) that has a polyurethane insert on the putter face, to which no particular function is ascribed. U.S. Pat. No. 5,458,332—Fisher (1995) discloses a putter face of polyurethane material of various hardness levels. These different hardness levels allow different rebound factors to change the feel and stroking force requirements. None of these references disclose a putter face with special friction characteristics and none identify any influence on ball direction or roll.
U.S. Pat. No. 6,497,626 B2—Sundberg (2002) and others show a putter face inclination of about 4° from vertical in order to provide a small amount of ball lift. No putters are disclosed which show a relationship of ball lift and roll with putter geometry and face surface condition.